Vehicular bodies such as automotive bodies are painted to provide not only improved appearances but also improved resistance to rust. The vehicle bodies would provide less commercial values if paint films formed on the bodies are damaged. The paint films are coated with water-based coatings in order to prevent deterioration of the commercial values.
The water-based coatings need to be evenly applied and spread to provide a uniform thickness, as in the case of painting of the vehicle bodies. Such even application of the water-based coatings is achieved using a nozzle unit disclosed in JP-B-3498941.
The disclosed nozzle unit will be discussed with reference to FIG. 14 hereof. As shown in FIG. 14, the nozzle unit denoted by reference numeral 100 includes a nozzle body 101, a plate member 102, and a plurality of bolts 103 connecting the plate member 102 to the nozzle body 101. The plate member 102 has a horizontal groove 105 for receiving a water-based coating fed from a feed port 104 formed in the nozzle body 101. The plate member 102 has a plurality of discharge passages 106 through which the water-based coating flows out.
Description will be made as to application of the water-based coating, fed from the nozzle unit 100, to a workpiece 110, with reference to FIG. 15.
As shown in FIG. 15, the water-based coating, designated at reference numeral 111, is fed from the nozzle unit 100 to the workpiece 110. Next, a roller 112 presses the protective coating 111 for spreading the coating 111 over the workpiece 110 to provide a protective film 113 on the workpiece 110.
The roller 112 is rotatably supported by levers 115 through pins 114. More specifically, opposite ends of the roller 112 are supported by the levers 115, 115. When the roller 112 is subjected to a reaction force from the workpiece 110, a roller center located furthest from the pins 114 flexes away from the workpiece 110. As a result, the protective film 113 is not rendered uniform in thickness.
Additionally, using the roller 112 for a long time inevitably leaves linear flaws on a surface of the roller 112. These linear flaws of the roller 112 leave a linear pattern on the protective film 113. This results in unpleasant outer appearance of the protective film 113.
There is a demand for an alternative to the above application method using the roller 113.